1. Field of the Invention
The present invention relates to a marking apparatus for forming desired marks such as characters, symbols, graphics, etc. on surfaces of contact lenses and particularly relates to an apparatus for marking contact lenses through screen-transfer of a predetermined print solution.
2. Background
Conventional methods for marking contact lenses include radiating a laser beam onto a contact lens in order to etch a mark in the lens, and radiating an ultraviolet-ray beam onto the contact lens after applying a dye solution to the lens to thereby adhere the dye solution to the contact lens. Since it is not practical to mark contact lens manually, various marking apparatuses have been devised.
For example, Japanese Patent Unexamined Publication No. Sho-53-40542 discloses a marking method comprising the steps of absorbing into a relief layer a solution containing diazonium salt (or a solution containing azo-coloring agent); bringing the relief layer into contact with a contact lens for a predetermined period of time to allow the solution to infiltrate and become dispersed in the contact lens; immersing the lens in a solution containing azo-coloring agent (or a solution containing diazonium salt) for a predetermined period to undergo a coupling reaction to thereby deposit a mark on the contact lens. Additionally, this publication discloses an apparatus which comprises a means for supporting a contact lens, and a collision/contact means including a movable collision/contact arm for supporting the relief layer in order to bring the relief layer into contact with a desired position of the contact lens and hold the lens in a contact state for a predetermined time.
Further, Japanese Patent Unexamined Publication (OPI) No. Sho-62-35093 discloses an apparatus which comprises a means for retaining a contact lens in a marking position, and cartridge means for supporting a film carrying a marking dye. In this apparatus, the cartridge means is fitted onto a platform provided with the lens holding means so that the film is pressed by the contact lens with a predetermined force. The contact state between the film and the contact lens is maintained for a predetermined time to thereby allow the dye to infiltrate into the contact lens. After the dye is transferred to the contact lens, the cartridge means is removed and a developing solution is applied to the lens to perform development of the mark.
In each of these marking apparatuses, however, the working efficiency is low because the process must be stopped while fixing the positions of the lens supporting means and the collision/contact means or the cartridge means in order to hold the contact lens and the film in a contact state until the dye solution or the like has sufficiently infiltrated into the contact lens.